The noninvasive ventilation (NIV) is a method of ventilatory support that does not require artificial airway. Its application is associated with complex hemodynamic repercussions, therefore is important to identify them for safety and effectiveness of the technique application.

The main objective of this research is to evaluate the hemodynamic repercussions using doppler echocardiography in healthy volunteers submitted a different values of positive end expiratory pressure (PEEP) by the following ventilatory modes: Continuous positive airway pressure (CPAP) and Bilevel.

The study hypothesis is that the positive end expiratory pressure (PEEP) may cause hemodynamic repercussions as: reduction of the ventricles pre-load, left ventricle after load, cardiac output and reduction in the diameter of the superior vena cava, due to the increase in the intrathoracic pressure and pulmonary volumes.

Inclusion Criteria:

• Healthy individuals
• Age between 18 and 40 years old
• Non smoker

Exclusion Criteria:

• Clinical signs or symptoms of any disease decompensation
• History of blood pressure variations by autonomic dysfunction
• Sense of claustrophobia
• Smoker